1. Field of the Invention
The invention relates to an incisal guide for dental articulators or the like provided with an upper and a lower component which are movable relative to each other by way of a joint, the incisal guide being mountable on the upper or lower component and provided with a guide surface inclined with respect to a reference plane upon which an incisal pin is supported and which, with a line of application of the greatest support force component denominated as normal, encloses an angle corresponding to the angle of protrusion and laterotrusion alignment of the human denture, the incisal pin, during simulated movement, moving across the predetermined incisal guide surface which may be selected and positioned by one or a combination of rotating, tilting, pivoting or shifting a guide surface block.
The dental articulator in essence corresponds to a motion simulator for representing mandible movements, these movements consisting of a translational as well as a rotational component of the axis of the joint of the jaws. In general, articulators are configured to consist of an upper and a lower component. As a rule, the impression model of the superior dental arch is mounted on the upper component and the impression model of the inferior dental arch is mounted on the lower component. In this connection, the models are mounted in a spatial alignment relative to a reference plane and to the jaw joint axis according to the conditions of an individual patient. The articulator is usually provided with two rear joint boxes which simulate the human jaw joint. By known methods the joint boxes are adjusted in all dimensions according to individual patients or according to statistical mean values. The posterior guides are predetermined in accordance with individual patients or statistical mean values and define the movements of the jaw joints in a translational direction of movement.
As regards the reconstruction of dental occlusal surfaces, the movement of the teeth relative to each other is decisive. During a laterotrusional movement, the crown of a lateral lower jaw tooth usually slides along a guide surface of the complementary opposite tooth on the upper jaw. The type of guide surfaces of all existing lateral teeth and their interaction during the course of their movement result in a so-called occlusion concept which in a natural set of teeth is usually shown as all teeth guiding during the initial laterotrusion movement, but that during continued excursion movement of the jaw joint the guides of the front teeth sequentially disocclude the rear teeth, i.e. the crown of the lower jaw tooth is lifted off the guide surface of the upper jaw tooth.
When fabricating prosthetic occlusion surfaces of teeth attempts are thus made to copy this occlusion guide concept in order to attain as high as possible a chewing efficiency in the prosthetic reconstruction. However, for reasons of dental medicine, dental technology or material technology, aside from the above mentioned natural sequential guide, other existing guide concepts (group function, canine guide, etc.) may be indicated.
2. The Prior Art
An incisal guide table is necessary for effectively putting such a concept of reconstruction into practice. Such tables as known, for instance, from German patent specifications DE 29 512 680 and DE 29 512 681 U1 are provided with a guide surface inclined relative to a reference plane. During movement, the incisal pin slides upon the guide surface. The forward slide surface forces the articulator into an additional rotational movement. This in common with the posterior controls of the two joint boxes results in the overall definition of the spatial lower jaw movement. It is thus possible, on the teeth of the upper jaw effectively to fabricate the steepness and disposition of the guide surface.
The guide surfaces of known incisal table systems are usually either permanently preset or they may be pivoted to, and arrested at, certain angles. Permanently preset Incisal table systems suffer from the drawback that during movement simulation they generate a guide system in which all teeth of one side guide simultaneously during laterotrusional movement. Often, such a guide concept is undesirable.
The complicated operation of adjustable incisal table systems has been found to be a disadvantage because for attaining guide surfaces, depending upon the concept, a different value, derived in advance by complex calculation with a computer program and displayed in a table, must be set for each tooth. Moreover, the use of such a system places high demands upon a dental technician. Often, the economic application and the putting into practice of a occlusion concept fails as a result of the complexity of the application and because the additional great complexity is not being paid for.